Main bearings are a constant source of confusion for early air-cooled Porsche owners. The Factory long ago stopped producing full sets and the engines can take a variety of different sizes, based upon year of manufacture and machine work to account for wear. Here's a handy guide to what bearings are available for your 356 or 912
The 356A and 356B were built with a three-piece engine case and a crankshaft with 50mm bearing journals. The bearing sets for this engine are listed with 546 part number prefixes.
The Super 90 (S90) came with a different crankshaft that had 55mm journals. These bearing sets are numbered 616-100-130-XX (where XX varies based upon sizing). While we do have the standard/standard size in stock, the sets for machined cranks are hard to source.
The 356C, SC and 912 engines had a 55mm crankshaft as well, but require a slightly different #1 bearing, These bearing sets are numbered in the 616-100-138-XX range.
To fix wear issues, you can machine the crankshaft and use a correspondingly thicker bearing. You can also line-bore the case to account for slight wear of the case. The naming conventions vary for this--some sheets have this listed as case (outside) / crank (inside) and others are crank (inside) / case (outside). Either way will work, as long as the part numbers match up to what you need. The below chart has it case / crank.
First machining is .25mm
Second machining is .50mm
Third machining is .75mm
Finally, our replacement main bearing sets typically use a modern steel-based bearing. We've replaced the prefix of each SET with NLA and listed this in the name and description of each bearing set. You can search on either the NLA- or 546/616 prefix to find what you need. We have individual bearings that are the original aluminum style as well.
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Main Bearing Sets: |
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546 prefix = 50 mm crank |
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616 prefix = 55 mm crank, incl S-90 |
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"1st/Std" = means case is 1st size larger / crank is Std size. Note, this order is listed differently than our print catalog, but the part numbers are the same and correct. |
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616-100-130-00 |
MAIN BRNGS,S-90, Std / Std |
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616-100-138-00 |
MAIN BRNGS,Std / Std |
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616-100-138-50 |
MAIN BRNGS, Std / 1st |
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616-100-138-55 |
MAIN BRNGS, Std / 2nd |
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616-100-138-60 |
MAIN BRNGS, 1st / Std |
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616-100-138-65 |
MAIN BRNGS, Std / 3rd |
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616-100-138-70 |
MAIN BRNGS, 1st / 1st |
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616-100-138-75 |
MAIN BRNGS, 1st / 2nd |
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616-100-138-85 |
MAIN BRNGS, 1st / 3rd |
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616-100-138-90 |
MAIN BRNGS, 2nd / Std |
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616-100-138-95 |
MAIN BRNGS, 3rd / Std |
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546-101-901-00 |
MAIN BRNGS,A/B, Std / Std |
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546-101-901-50 |
MAIN BRNGS,A/B,Std / 1st |
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546-101-901-55 |
MAIN BRNGS,A/B, Std / 2nd |
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546-101-901-60 |
MAIN BRNGS,A/B, 1st / Std |
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546-101-901-70 |
MAIN BRNGS,A/B, 1st / 1st |
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546-101-901-75 |
MAIN BRNGS,A/B, 1st / 2nd |
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546-101-901-85 |
MAIN BRNGS,A/B, 1st / 3rd |
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Rod Bearing Sets: |
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for "late" rods only |
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616-103-142-02-SET |
ROD BRNG SET,Std |
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616-103-142-52-SET |
ROD BRNG SET, 1st |
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616-103-142-62-SET |
ROD BRNG SET,2nd |
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616-103-142-72 |
ROD BRNG Indiv 3rd |